When drilling holes into the earth, a string of drill pipe is rotated and driven into the earth to form the hole. The end of the string of drill pipe includes a cutting head which dislodges the earthen material as the drill pipe string is driven deeper into the earth. Water is typically flowed into the hole being drilled, with the water and removed earthen material flowing upwardly around or within the rotating drill pipe and outwardly of the hole being drilled.
The apparatus which rotates the drill string is of course subjected to a counter rotational force in a direction opposite to the direction the drill string is rotated. The larger the diameter of the cutting head at the end of the drill string, the larger the counter rotational force or torque for a given speed of rotation of the drill pipe string. In some instances, the cutting head diameter can reach up to 20 feet, and beyond. Needs remain for improved manners of contending with the counter rotational force where cutting head diameters exceed about 10 feet in diameter.
While the invention was motivated in addressing the above identified issues, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents.